There is a device for cleaning vehicular exhaust gas, in particular a diesel exhaust particle filter, comprising a one-piece filter body which has gas flowing through it and is composed of a plurality of cuboid individual bodies and, as seen in cross-section, has a round outer contour deviating from a circular shape, the individual bodies located in the interior of the filter body having a square cross-section delimited by side faces, and neighboring, machined individual bodies having plane side faces adjoining the side faces of the internal individual bodies.
Such filter bodies usually are composed of extruded one-piece monolithic individual bodies which are glued to each other and in particular are made from SiC material, these elongate individual bodies in their commercially available form preferably having a square cross-section. On one end face, the individual bodies have numerous inflow channels which end in a blind hole each, are arranged honeycomb-like and which in particular have a square cross-section, and adjoining to these the individual bodies have effusion channels which have no direct flow connection and are formed by likewise honeycomb-like blind holes, more specifically square blind holes as seen in cross-section, emanating from the opposite end face. The exhaust gas flows from the inflow side end wall into the numerous channels, diffuses through the adjoining wall to the effusion channels, while the carbon particulate matter is retained in the inflow channel. The exhaust gas catalytic converters are appropriately constructed from coated filter bodies. The filter body composed of individual bodies is machined on the outside, is in particular turned on a lathe. Up to now, there are installed elongate filter bodies, among other things, which have a circular outer contour. Meanwhile, however, one has started thinking about filter bodies which are provided with a round outer contour deviating from a circular shape, which in particular are larger in width than in height, so that they have as small an overall height as possible in the region of the underbody.
One example of a contemplated filter body of this type is illustrated in FIG. 1. This filter body has an oval, more specifically even an elliptic outer contour and is composed of 18 individual bodies in total. Six individual bodies 2 having a square cross-section and an unmachined outer circumference are located in the interior of the filter body, and are surrounded by machined individual bodies 4 and 6. Here, the eight individual bodies 4 are formed by eight originally square, unmachined individual bodies which are machined on the outside not until the composite is obtained. The four smallest individual bodies 6 are produced by two individual bodies which are sawn up in the longitudinal direction into two small sections. These sections are then glued into the corresponding gaps. In this known filter body, it is laid great importance to the fact to accommodate as many individual bodies—as in fact unmachined individual bodies—in the interior of the filter body as possible, i.e. as many individual bodies 2 as possible. This is due to the fact that the external, machined individual bodies will loose a superproportionally large active filter surface area with respect to internal, unmachined individual bodies with square end face. This means that the individual bodies machined on their circumference loose considerably more filtering capacity than cross-sectional surface, as seen in relation to the unmachined individual bodies. In the embodiment of FIG. 1 according to prior art there is needed a total of 18 individual bodies for the filter body.